Devices and methods for vertebral stabilization

ABSTRACT

Devices, systems and methods for the treatment of spinal instability and/or stenosis of the spinal canal and neural foramina. In one embodiment, a functional spinal unit (FSU) of a subject is approached through a lateral or antero-lateral corridor, and both an anterior and posterior column of the FSU are manipulated, implanted and/or otherwise surgically treated through the same intra-abdominal surgical corridor. A method is disclosed to reach the posterior aspect of the FSU, wherein the intra-abdominal surgical corridor is extended posterior to the psoas major muscle and through the thoraco-lumbar fascia in order to reach the transverse process and/or facet joint. Multiple trajectories for bone screw fixation of the vertebral bone are additionally disclosed. In another embodiment, the FSU is approached through the above corridor and a second posterior skin incision and corridor. The combination of the corridors provided circumferential access to the FSU.

PRIORITY

This application is a continuation of and claims priority to co-ownedU.S. patent application Ser. No. 15/294,382 filed on Oct. 14, 2016 andentitled “DEVICES AND METHODS FOR VERTEBRAL STABILIZATION”, which claimspriority to U.S. Provisional Patent Application Ser. No. 62/284,944entitled “SPINAL FIXATION DEVICES AND METHODS OF USE”, filed Oct. 14,2015, each of the foregoing incorporated herein by reference in itsentirety.

COPYRIGHT

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND 1. Field of the Disclosure

This disclosure relates generally to bone fixation systems, componentsthereof, and methods of implant placement for adjusting, aligning andmaintaining the spatial relationship(s) of adjacent bones or bonyfragments, such as for example after surgical reconstruction of skeletalsegments.

2. Description of Related Technology

Whether from degenerative disease, traumatic disruption, infection orneoplastic invasion, alteration in the anatomical relationships betweenthe spinal vertebras can cause significant pain, deformity anddisability. Spinal disease is a major health problem in theindustrialized world, and the surgical treatment of spinal pathology isan evolving discipline. The traditional surgical treatment of abnormalvertebral motion is the complete immobilization and bony fusion of theinvolved spinal segment and an extensive array of surgical techniquesand implantable devices have been formulated to accomplish the treatmentobjective.

Regardless of the specific objectives of surgery, many surgeons employimplantable devices that maintain the desired spatial relationship(s)between adjacent vertebral bodies. The effectiveness of these devices iscritically dependent on adequate fixation into the underlying bone.Adequate access and fixation of both the anterior and posterior spinalcolumns often requires multiple incisions and surgical corridors.Therefore, such procedures continue to be substantial operations with amultitude of shortcomings, including without limitation increased traumato the patient, extended recovery time after surgery, and enhanced riskfor surgical complications such as infection. Such problems can furtherbe exacerbated when the patient is elderly, and/or has compromisedphysiology in one respect or another.

Hence, there is a salient need for alternative methods of implantplacement and bony fixation, and associated apparatus, in order to,inter alia, reduce the necessary degree and scope surgery and associatedsurgical risk, particularly in aging populations.

SUMMARY

The present disclosure addresses the foregoing needs by disclosing,inter alia, apparatus and methods for the treatment of abnormal spinalstability and stenosis of the spinal canal, including by providingdecompression and/or fixation thereof.

In a first aspect, a method for stabilization of an anatomical portionof a subject is disclosed. In one embodiment, the anatomical portioncomprises a target functional spinal unit (FSU) of a living subject, andthe method includes: (i) forming a first tissue corridor; (ii) accessingand manipulating an anterior portion of the target FSU via the firsttissue corridor; (iii) forming a second tissue corridor; and (iv)accessing and manipulating a posterior portion of the target FSU via thesecond tissue corridor.

In one variant, the forming a first tissue corridor includes forming thecorridor from a skin incision to a side surface of the target FSU, withthe first tissue corridor extending at least partially through anabdominal cavity of the subject.

In another variant, the forming of the second tissue corridor includesforming a corridor that is extended posterior to a psoas major muscleand through a thoraco-lumbar fascia of the subject.

In another embodiment, the method includes: (i) forming a tissuecorridor from a skin incision to a side surface of the functional spinalunit, the tissue corridor extended at least partially through anabdominal cavity of the subject; (ii) accessing an anterior portion ofthe target FSU through the tissue corridor; and (iii) accessing alateral aspect of an ipsilateral pedicle of an inferior vertebral boneof the target FSU, and (iv) advancing at least one bone fastener intothe inferior vertebral bone, the at least one bone fastener extended ina lateral to medial trajectory.

In yet another embodiment, the method includes: (i) forming a tissuecorridor from a skin incision to a side surface of the target FSU, thetissue corridor extended at least partially through an abdominal cavityof the subject; (ii) accessing an anterior portion of the target FSUthrough the tissue corridor and positioning an orthopedic implant withinan intervertebral disc space of the target FSU; (iii) extending thetissue corridor posterior to a psoas major muscle; and (iv) accessing alateral surface of a superior articulating process of a facet joint ofthe target FSU via the extended tissue corridor.

In yet a further embodiment, the method includes: (i) forming a firsttissue corridor from a skin incision to a side surface of the targetFSU, the first tissue corridor at least partially extended through anabdominal cavity of the subject; (ii) accessing an anterior portion ofthe target FSU through the first tissue corridor; (iii) extending thefirst tissue corridor posterior to a psoas major muscle; (iv) accessingan anterior surface of a transverse process of the target FSU via theextended first tissue corridor; (v) forming a second tissue corridorfrom a posterior skin incision one a back of the subject to a posterioraspect of at least one vertebral bone of the target FSU; and (vi)advancing a bone fastener into the posterior aspect of the at least onevertebral bone via the second tissue corridor.

In still another embodiment, the method includes: (i) forming a tissuefrom a skin incision to a side surface of the target FSU, the tissuecorridor extended at least partially through an abdominal cavity of thesubject; (ii) accessing an anterior portion of the target FSU throughthe tissue corridor; and (iii) advancing at least one bone fastenerthrough a side surface of a body segment of a vertebral bone of thetarget FSU. In one variant, the trajectory of the at least one bonefastener is extended in an anterior to posterior direction and enters atleast a segment of a pedicle portion of the vertebral bone to which thefastener is attached.

In a second aspect, a method for accessing a targeted functional spinalunit (FSU) for manipulation and/or fixation is disclosed. In oneembodiment, the method includes: (i) creating at least one first tissuecorridor through at least one of flank skin and/or abdominal skin of asubject to an anterior or a lateral portion of the targeted FSU; and(ii) creating at least one second tissue corridor through posterior skinof the subject.

In one variant, the second corridor extends along a plane between theipsilateral psoas major muscle and the quadratus lumborum muscle to aposterior portion of the targeted FSU, and the at least one first tissuecorridor comprises a direct anterior approach.

In another variant, the at least one first tissue corridor comprises ananterolateral approach. In yet another variant, the at least one firsttissue corridor comprises a direct lateral approach.

In still another variant, the first tissue corridor extends at leastpartially through an abdominal cavity of the subject.

In a third aspect, a method for immobilization of a facet joint of atargeted FSU is disclosed. In one embodiment, the method comprises: (i)removing at least a portion of a nucleus pulposus of an intervertebraldisc space of the facet joint via a first tissue corridor; (ii)implanting one or more orthopedic implants into an intervertebral discspace of the facet joint via the first tissue corridor; and (iii)attaching one or more bone fasteners to the targeted FSU via advancementthrough a second tissue corridor. In one variant, the first tissuecorridor is formed through flank skin and/or abdominal skin of a subjectto an anterior or a lateral portion of the targeted FSU. In anothervariant, the second tissue corridor is formed through posterior skin ofthe subject along a plane between the ipsilateral psoas major muscle andthe quadratus lumborum muscle to a posterior portion of the targetedFSU.

In yet another variant, the method further comprises removal of one ormore of the ipsilateral transverse processes of a superior and/orinferior vertebral bone of the targeted FSU via the second tissuecorridor. In one implementation, at least a portion of the removed oneor more ipsilateral transverse processes is inserted into theintervertebral disc space and utilized as a bone graft material for theone or more implants.

In a fourth aspect, a method of providing decompression of spinalstenosis is disclosed. In one embodiment, the method comprises: (i)accessing a facet joint of a target FSU via a tissue corridor, thetissue corridor extended posterior to a psoas major muscle, anterior toa quadratus lumborum muscle, and through a thoraco-lumbar fascia; and(ii) removing at least a portion of the ipsilateral facet joint. In onevariant, the method further comprises rigidly fixing a position of thetarget FSU via one or more orthopedic implants and/or bone fastenersadvanced through the tissue corridor.

In another aspect, a method of achieving circumferential access to anFSU is disclosed. In one embodiment, the method includes approaching theFSU through an intra-abdominal corridor, as well as a second posteriorskin incision and corridor. The combination of the intra-abdominalcorridor and second posterior corridor provide circumferential access tothe FSU.

In another aspect of the disclosure, an implantable bone fastenerassembly is disclosed. In one embodiment, the bone fastener assemblyincludes a threaded bone screw with threaded shaft and a shaped (e.g.,spherical) head portion. In one variant, an internal bore extendsthrough the internal aspect of the screw, extending from the top of thehead portion to a tip of shaft. The internal bore in one implementationincludes a threaded portion, and a polygonal (e.g., hex) shapedreceptacle resides within the head.

In another implementation, an outer housing is included, and has aninternal seat adapted to seat the head of the screw. The housing alsohas an additional seat that is adapted to accept an inter-connectingmember, such as a rod.

In a further aspect, a system for spinal treatment is disclosed. In oneembodiment, the system includes at least first and second bone fastenerelements for fixation to respective bones or bone portions of the spineof the subject, and a connecting element (e.g., rod) for mechanicalstabilization of the spine. One or more inter-disc implants are alsoutilized as part of the system.

In yet other aspects, methods and apparatus for treating patients aredisclosed.

The details of one or more embodiments are set forth in the accompanyingdrawings and description below. Other features, objects, and advantageswill be apparent from the following description, the accompanyingdrawings and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are a side elevation view, a top plan view, and a posteriorelevation view, respectively, of an exemplary vertebral bone.

FIGS. 2A and 2B are a posterior elevation view and a posteriorperspective view of an exemplary functional spinal unit (FSU) comprisedof two adjunct vertebral bones and an intervening disc space.

FIG. 3 is a schematic representation of a subject illustrating thepositioning of the subject on an operating table.

FIG. 4 is a schematic representation of a human torso in cross-section.

FIG. 5 is a top plan view of a subject's spine illustrating multipleapproach corridors to the target vertebral bone.

FIG. 6 is a cross-sectional view of a subject's spine and surroundinganatomy.

FIG. 7 is a cross-sectional view of a subject's spine and surroundinganatomy illustrating approach Corridor C.

FIGS. 8A and 8B are top plan views of a subject's spine illustratingaccess and possible resection of the transverse process via Corridor C.

FIG. 9 is an anterior perspective view of a target FSU.

FIGS. 10A and 10B are posterior perspective and top plan views of asubject's spine, respectively, illustrating access of the facet jointvia Corridor C.

FIGS. 11A and 11B are side elevation and posterior perspective views ofa subject's spine, respectively, illustrating a trajectory of a bonescrew used to fixate the facet joint.

FIGS. 12A and 12B are each perspective and cross-sectional views of anembodiment of a facet screw/fastener assembly.

FIGS. 13A and 13B and 14 are anterior perspective views (FIGS. 13A and13B) and a posterior perspective view (FIG. 14) of a subject's spineillustrating the facet screw/fastener of FIGS. 12A and 12B in place.

FIGS. 15 and 16 are top perspective views and a cross-sectional view,respectively, of a bone fastener assembly that is adapted to couple withan interconnecting rod.

FIG. 17 is an anterior perspective view of a subject's spin illustratingthe bone fastener assembly of FIGS. 15 and 16 in use.

FIGS. 18A and 18B are a top plan view and side perspective views of asubject's spine illustrating a position and a trajectory of a bonescrew/fastener assembly.

FIGS. 19A and 19B are a side perspective view and a schematicrepresentation of a subject's spine illustrating a corridor and a bonesegment for bone screw/fastener placement.

FIGS. 20A and 20B are top plan views of a subject's spine illustratingadditional embodiments of bone screw/fastener placement.

FIGS. 21A and 21B are top plan views of a subject's spine illustratingadditional embodiments of interbody implant and bone screw/fastenerplacement.

FIG. 22 is a schematic cross-section view of a subject's spine andsurrounding anatomy illustrating an additional embodiment of corridorsto access the target vertebral bone.

FIGS. 23A and 23B are cross-sectional views of a subject's spineillustrating additional embodiments of bone screw/fastener placement.

FIG. 24 is cross-sectional view of a subject's spine and surroundinganatomy illustrating an additional embodiment of corridors to access thetarget vertebral bone.

FIGS. 25A-25C are top plan views of a subject's spine illustratingdecompressions that may be accomplished through the access corridors.

FIGS. 26A-26C are side elevation views of a subject's spine illustratingperformance of a pedicle subtraction osteotomy through the accesscorridors, and a potential use of a lordotic implant in performing apedicle subtraction osteotomy.

All Figures ©Copyright 2013-2016. Samy Abdou. All rights reserved.

DETAILED DESCRIPTION

In order to promote an understanding of the principals of thedisclosure, reference is made to the drawings and the embodimentsillustrated herein. Nevertheless, it will be understood that thedrawings are illustrative and no limitation of the scope of the claimsis intended thereby. Any such alterations and further modifications inthe illustrated embodiments, and any such further applications of theprinciples of the disclosed devices as illustrated herein arecontemplated as would normally occur to one of ordinary skill in theart.

Overview

In one aspect, improved devices, systems, and methods for the treatmentof abnormal spinal stability and/or stenosis of the spinal canal aredisclosed. Specifically, methods for fusion of a superior vertebral boneto an inferior vertebral bone of a target functional spinal unit aredisclosed that, inter alia, overcome the disabilities of the prior artdescribed above.

In one embodiment, a skin incision is made in a flank skin and/orabdominal skin of a subject on one side of the mid-sagittal plane thatdivides the subject into right and left sides. For example, the incisioncan be positioned anterior to coronal plane T. An intra-abdominal (and,in some examples, extra-peritoneal) surgical corridor is developed fromthe skin incision through a plane between the ipsilateral psoas majormuscle and the ipsilateral quadratus lumborum muscle, and across coronalplane T in anterior to posterior trajectory. Optionally, the ipsilateraltransverse process of one or both vertebral bones of the targetfunctional spinal unit may be removed, such as, e.g., the ipsilateraltransverse process of the inferior vertebral bone of the targetfunctional spinal unit. When removed, the harvested transverse processmay be used, if desired, as a portion of the bone graft material used tofuse the superior and the inferior vertebral bone to one another.

In one implementation, the ipsilateral facet joint may be accessedthrough corridor C and at least partially removed, if desired, todecompress the nerve elements. The ipsilateral facet joint, whetherwhole or after partial resection, may be then implanted with one or morefasteners that serve to immobilize and/or limit movement across thefacet joint. In some examples, the target intervertebral disc space isalso entered, at least a portion of the contained nucleus pulposus isevacuated, and the disc space is then implanted with bone graft materialand/or an orthopedic implant that is configured to fuse the adjacentvertebral bone. Additionally, in some examples, at least some of thebone used for the disc space fusion (also known as interbody fusion) maybe derived from the resected transverse process. The disc space canadvantageously be entered through one of the three potential sites, suchthat the disc space work may be performed prior to fastener placementand immobilization of the ipsilateral facet joint.

In another embodiment, the target intervertebral disc space may beentered anterior to the ipsilateral psoas and posterior to the aorta(such as, e.g., an anterolateral approach 507 shown in FIG. 5). At leasta portion of the nucleus pulposus is removed and the disc space isimplanted with an orthopedic device configured to permit interbodyfusion across the target disc space. After the disc is implanted withthe orthopedic device, corridor C is used to access the lateral aspectof the ipsilateral facet joint of the target functional spinal unit anda bone fastener is placed across the facet joint in a lateral to medialtrajectory. Advantageously, the implantation of the targetintervertebral disc space may be performed before or after access of theipsilateral facet joint; e.g., prior to facet immobilization with thefastener.

In additional embodiments, several other methods for vertebral fixationare disclosed wherein corridor C is used to access the anterior aspectof the ipsilateral transverse process and the lateral ipsilateralpedicle to which it is attached.

Further, various bone screw trajectories are disclosed for use in thedisclosed methods of vertebral fixation.

Furthermore, methods for placement of bone screws into the ipsi- orcontra-lateral pedicles from lateral or antero-lateral screw insertionsite (into the vertebral body) are described.

Detailed Description of the Exemplary Embodiments

Described herein are devices, systems and methods for the treatment ofabnormal spinal stability and stenosis of the spinal canal. In anexemplary embodiment of the invention, the spine is approached through alateral (i.e., side) corridor or an anterolateral corridor, and both theanterior and posterior columns of the spine are manipulated, implantedand/or otherwise surgically treated through the same intra-abdominalsurgical corridor. Any of these surgical corridors, whileintra-abdominal, may also be extra-peritoneal (i.e., corridors with donot traverse the peritoneal cavity).

FIGS. 1A-1C show diagrammatic representations of a spinal vertebral bone802 in multiple views. For clarity of illustration, the vertebral boneof FIGS. 1A-1C and those of other illustrations disclosed herein arerepresented schematically and it should be appreciated that actualvertebral bodies may include anatomical details that are not shown inthese figures. Specifically, actual vertebral bodies may vary in anatomyfrom the idealized vertebral bones illustrated in the drawings, whetherbecause of congenital or acquired deformity, spondylotic change (such asbony spurs and the like), spinal malalignment and/or other changes. Fordescriptive purposes, idealized vertebral bones are assumed.

The term “sagittal plane”, as used herein, refers to the plane thatsplits the body into left and right segments. The “mid-sagittal plane”or “median plane” splits the body into equal left and right halves. Theterm “coronal plane”, as used herein, is the plane that divides the bodyinto anterior (front) and posterior (back) segments. Hence, the coronaland sagittal planes are perpendicular to one another.

Further, it will be understood that the vertebral bones at a given level(i.e., in a given spinal section) of the spinal column of a human oranimal subject will contain anatomical features that may not be presentat other levels of the same spinal column. The illustrated vertebralbones are intended to generically represent vertebral bones at anyspinal level without limitation. The disclosed devices and methods maybe employed at any applicable spinal level.

Vertebral bone 802 contains an anteriorly-placed vertebral body 804, acentrally placed spinal canal 806 and posteriorly-placed lamina 808. Thepedicle segments 810 of vertebral bone 802 form the lateral aspects ofthe spinal canal 806 and connect the laminas 808 to the vertebral body804. The spinal canal 806 contains neural structures such as the spinalcord and/or nerves. A midline protrusion termed the spinous process SPextends posteriorly from the medial aspect of laminas 808. A protrusionextends laterally from each side of the posterior aspect of thevertebral bone 802 and is termed the transverse process TP.

A right transverse process RTP extends to the right from the lateralaspect of the right pedicle. A left transverse process LTP extends tothe left from the lateral aspect of the left pedicle. A superiorprotrusion extends superiorly above the lamina 808 on each side of thevertebral midline and is termed the superior articulating process SAP.An inferior protrusion extends inferiorly below the lamina 808 on eachside of the vertebral midline and is termed the inferior articulatingprocess IAP. Note that the posterior aspect of the pedicle 810 can beaccessed at an indentation 811 in the vertebral bone 802 between thelateral aspect of the SAP and the medial aspect of the transverseprocess TP. In surgery, it can be common practice to anchor a bonefastener into the pedicle portion 810 of a vertebral bone 802 byinserting the fastener through indentation 811 and into the underlyingpedicle 810 in a posterior to anterior direction.

FIGS. 2A and 2B illustrate a functional spinal unit (FSU), whichincludes two adjacent vertebrae and the intervertebral disc disposedbetween the adjacent vertebrae. The intervertebral disc resides betweenthe inferior surface of the upper vertebral body and the superiorsurface of the lower vertebral body, although it is not specificallyshown in the figures. FIG. 2A shows the posterior surface of theadjacent vertebrae and the articulations between them. FIG. 2B shows analternate oblique view of the identical structure. The FSU containsthree joints between the two vertebral bones, with the intervertebraldisc comprising the anterior joint. The posterior joints include a facetjoint 814 on each side of the midline, wherein each facet joint 814 iscomprised of the articulation between the inferior articulating process(IAP) of the superior vertebral bone and the superior articulatingprocess (SAP) of the inferior bone. These and other illustrations anddefinitions of anatomical structures are known to those of ordinaryskill in the art. They are described in more detail in Atlas of HumanAnatomy, by Frank Netter, third edition, Icon Learning Systems,Teterboro, N.J., which is hereby incorporated by reference in itsentirety. It will be appreciated that the directional language and termsregarding orientation (such as “upper”, “lower”, “upward”, “downward”,etc.) are used throughout merely for convenience of description and arenot intended to be limiting.

At the spinal segment to be surgically treated via the disclosedmethods, a coronal plane T (which is a vertical plane of the subject'sbody) may be defined to contain the most anterior point of each of theright and left transverse processes. In general, the most anteriorsegment of each transverse process is found at its medial border withthe lateral anterior border of the pedicle to which it is attached.Coronal plane T is illustrated in FIGS. 1B and 3. Further, a coronalplane U (FIG. 1B) may be defined as the plane of the posterior wall ofthe vertebral body when considered at the level of the superior corticalsurface of said vertebral body. In this way, the foregoing coronalplanes may be used to define an anterior vertebral segment and aposterior vertebral segment.

Some medical literature uses coronal plane U as a dividing line betweenthe anterior and posterior vertebral segments (such as, e.g., in the twocolumn model of the spine). (See, e.g., “The three column spine and itssignificance in the classification of acute thoracolumbar spinalinjuries.” By Denis F. Spine 1983 November-December; 8 (8):817-31, whichis herein incorporated by reference in its entirety.) While eithercoronal plane U or coronal plane T can be used to define the boundarybetween the anterior and posterior segment of the vertebral bone, forthe purposes of the present disclosure, coronal plane T is employed asan exemplary boundary plane, however coronal plane U can be additionallyor alternatively employed.

A subject requiring surgery on a segment of their lumbar spine may bepositioned on the operating table in the supine, prone, lateraldecubitus or a combination of these positions. For example, a patientmay be positioned between supine (i.e., his back at zero degreesrelative to the OR table) and lateral positions (i.e., his back atninety degrees to the OR table) with one side of the pelvis positionedfurther above the OR table than the other pelvic side. In one example,the subject is positioned in the lateral decubitus position as show inFIG. 3. In this example, the patient is positioned with the left lateralside up (i.e., away from the operating table) and the mid-sagittal planeof the spine parallel to the floor. The lumbar segment to be surgicallytreated is comprised of at least a superior vertebral bone, animmediately inferior vertebral bone and the intervening intervertebraldisc space. The FSU to be surgically treated will be referred to as the“target FSU” and its intervertebral disc space as the “targetintervertebral disc space”.

An exemplary method of device implantation is now illustrated. First, atarget FSU is identified for surgical manipulation and treatment. Inpreparation for surgery, the patient may be placed in the abovedescribed lateral decubitus position (FIG. 3). The level of the spinethat is to be implanted can be localized on an imaging modality (such asX-ray, CT, Mill and the like) in at least one plane. After customarysterilization and/or other preparation of the operative site, thesurgeon can localize an incision point on the skin that is anterior tocoronal plane T. In one implementation, the incision may be madeimmediately anterior to a coronal plane that is parallel to coronalplane T and passes through the anterior-most (tip) aspect of the targetdisc space. In other words, an incision is made in a segment of the skinof the subject that is anterior to coronal plane T but lateral tomid-sagittal plane that divides the body into right and left sides.

A surgical corridor is developed through the extra-spinal tissue fromthe incision until the target FSU is reached, wherein the corridor tothe target disc space is at least partially anterior coronal plane T. Inone embodiment, the target intervertebral disc space is entered and atleast a portion of the viscoelastic material that comprises the naturalnucleus pulposus is removed. For example, in the lumbar vertebradepicted in FIG. 5, the disc space may entered in at least one or moreof the three following locations: a) medial to the aorta and maycomprise the midline (and/or its branches, the common iliac arteries,etc.) to form a direct anterior approach 505; b) lateral to the aortabut anterior to the ipsilateral psoas major muscle to form ananterolateral approach 507, in which the ipsilateral psoas major muscleis ipsilateral to the skin incision used to develop the surgicalcorridor; and c) laterally and through the body of the ipsilateral psoasmajor muscle to form a direct lateral approach 509. In another example,a lateral corridor “V” (shown in FIG. 4) can be made from the flankincision and taken onto the target intervertebral disc space.

The disc space may be entered using at least one or more of the examplecorridors shown in FIG. 5. In one implementation, the targetintervertebral disc space is entered using an anterolateral approach(such as, e.g., anterolateral approach 507 shown in FIG. 5), which is atleast partially positioned between the lateral aorta and the anteriorsurface of the ipsilateral psoas major muscle.

If desired, after removal of viscoelastic material, an orthopedicimplant may be implanted into the target intervertebral disc space usingthe same surgical corridor and then left in place after surgery iscomplete. In this specific example, after removal of at least a portionof the nucleus pulposus of the target intervertebral disc space, animplant 206 may be placed into the disc space (FIG. 10A). In anexemplary embodiment, implant 206 extends across the mid sagittal planeof the disc space and has one end segment positioned onto the left sideof the apophyseal ring of the inferior vertebral bone and a second endsegment positioned on the right side of said apophyseal ring. Theoperation, when performed using a trans-psoas corridor 509, is known tothose skilled in the art as the “XLIF” procedure, among other names.(See “Extreme Lateral Interbody Fusion (XLIF): a novel surgicaltechnique for anterior lumbar interbody fusion.” By Ozgur, Aryan et al.in Spine J. 2006 July-August; 6 (4):435-43, which is herein incorporatedby reference in its entirety.)

Additionally, the superior and inferior vertebral bones may bedistracted away from one another in order to increase the verticalheight of the target intervertebral disc space. The optional distractionstep may be performed with distraction instrument(s) that aretransiently used during surgery and then removed prior to the end of theprocedure, and/or by the orthopedic implant(s) that is positioned duringsurgery and left in place. Whether the target intervertebral disc spaceis entered and manipulated or not, at least a portion of the surgicalcorridor may be oriented so as to extend through the anterior layer ofthe thoracolumbar fascia. (A full description of the anatomy of thethoracolumbar fascia is contained in: The thoracolumbar fascia: anatomy,function and clinical considerations. Willard F H, et al. J Anat. 2012December; 221 (6): 507-536., which is herein incorporated by referencein its entirety.)

In another implementation, development of a surgical corridor C isillustrated in FIGS. 6 and 7. As shown, corridor C is developed betweenthe posterior aspect of the ipsilateral psoas major and the anterior andmedial aspect of the ipsilateral quadratus lumborum muscle. Whilecorridor C is intended to substantially extend between these twomuscles, it may contain at least a segment of each of them. Corridor Cis thereby intended to be anterior to the anterior surface of theipsilateral transverse process of the inferior vertebral bone of thetarget FSU and posterior to at least the posterior half of theipsilateral psoas major muscle (when the latter is taken in a sagittalplane that traverses it).

In the superior lumbar spine, the psoas is usually a small muscle and itincreases in size as it extends inferiorly. In some segments of thespine, such as the thoracic spine, the psoas major muscle is not presentat all. Where the muscle is absent, it is understood that corridor C isdefined by its relationship to the ipsilateral transverse process andnot by its relationship to the psoas muscle. In some examples, theanterior layer of the thoracolumbar fascia is traversed by corridor C.Dissection may be continued through corridor C in order to traversecoronal plane T in an anterior to posterior direction. In this way, theipsilateral transverse processes of the vertebral bones of the targetFSU may be reached. Similarly, segments of the target functional spinalunit that are positioned posterior to coronal plane T may be accessedthrough corridor C.

If desired, the ipsilateral transverse process of either said superioror inferior vertebral bone of the target functional spinal unit may beremoved through corridor C (FIGS. 8A and 8B). The harvested transverseprocess bone may be used as autograft bone for a fusion procedure thatis concurrently performed at the same operation. In other words, thepreceding steps constitute a method for removal of a transverse processof the target FSU. In this exemplary method, an intra-abdominal (and, insome examples, extra-peritoneal) surgical corridor is developed througha plane between the ipsilateral psoas major muscle and at least asegment of the ipsilateral quadratus lumborum muscle. Subsequently, theipsilateral transverse process of one or both vertebral bones of thetarget functional spinal unit is removed.

The removed transverse process may be used as a bone graft (i.e.,autograft) material to fuse two or more skeletal bones of the individualduring the same surgical procedure (if desired). In one embodiment, theharvested transverse process bone is incorporated into the bone graftthat is used to fuse the superior vertebral bone to the inferiorvertebral bone of said target functional spinal unit. For example, atleast a portion of the bone graft that is used to fuse superior toinferior vertebral bones (by positioning a segment of the bone graft toabut the superior vertebrate bone and a segment to abut the inferiorvertebral bone) is comprised of bone derived from the harvestedtransverse process.

At least a portion of the harvested transverse process bone may beplaced into the target intervertebral disc space in order to form aninterbody fusion within the target functional spinal unit. Further, bonegraft material (whether containing autograft bone, allograft bone, asynthetic material, or any other substance adapted to form bone) may beplaced to extend along the longitudinal axis of the spine from thelateral aspect of the superior articular process (SAP) of the superiorvertebral bone to the superior articular process (SAP) of the inferiorvertebral bones of the target functional spinal unit. The bone graftmaterial will eventually form a fusion mass that connects the SAP andtransverse processes (or the remaining stump thereof) of adjacentvertebral bones (FIG. 8B).

As depicted in FIG. 9, a facet joint, by definition, is an articulationcomprised of the superior articulating process (SAP) of an inferiorvertebral bone and the inferior articulating process (IAP) of theimmediately superior vertebral bone. In the target FSU, right and leftfacet joints form articulations between the superior and inferiorvertebral bone with a single facet joint on each side of the midsagittal plane of the vertebral column. Using corridor C to reach theipsilateral transverse process, as described above, the ipsilateralfacet joint (ipsilateral to the skin incision) can be also accessed.

In one embodiment, the ipsilateral transverse process of the inferiorvertebral bone of the target FSU is removed in order to provide a widercorridor through which to access the ipsilateral facet joint. However,it will be understood that the transverse process may be left in placeor only partially removed and the ipsilateral facet joint accessedaround the transverse process. When the transverse process is not fullyremoved, the facet joint may be accessed through an anterior toposterior trajectory that passes superior to said ipsilateral transverseprocess of the inferior vertebral bone, as shown in FIGS. 10 A and 10B.The trajectory used to access the ipsilateral facet joint via corridor Cwill necessarily cross coronal plane T in an anterior to posteriortrajectory (FIG. 10B) and will substantially follow member 200. Notethat the tip of member 200 is positioned at the lateral surface of theSAP of the inferior vertebral one of the target FSU.

The preceding steps constitute a method to access the ipsilateral facetjoint between the superior and inferior vertebral bones of a target FSU.Once accessed, the ipsilateral facet joint may be least partiallyremoved, if desired, to decompress the nerve elements. The joint,whether whole or after partial resection, may be also implanted withfastener(s) that serve to limit and/or completely immobilize movementbetween the superior and inferior vertebral bones, as will be furtherdiscussed below.

After the ipsilateral facet is accessed through corridor C, one or morefixation devices (such as, e.g., a bone screw and/or the like) may beused to limit movement and/or immobilize the facet joint. For example,FIG. 10A shows an illustrated spine with implant 206 positioned withinthe L4/L5 disc space. As described above, the implant 206 may be placedinto the target disc space via the antero-lateral corridor 507. In someexamples, the anterior column implant is placed first and then thesurgical corridor is turned posteriorly in order to access theipsilateral facet joint through the corridor anterior to the ipsilateralquadratus lumborum (corridor C).

In regions of the spine where the psoas muscle is large (such as L3 toL5), corridor C may be posterior to the psoas muscle. While the anteriorimplant 206 is, in some examples, implanted prior to facet joint access,either the disc space work or the facet joint access may be performedfirst. (Many embodiments of interbody implants are known in the art.U.S. Pat. Nos. 4,636,217; 5,015,247; 5,192,327; 5,443514; 5,749,916,6,251,140; 6,342,074; 6,706,070; 6,767,367; 6,770,096; 6,852,127;7,037,339; 7,227,477; 7,641,690, among others, disclose some of theseinter-body implant device. Each of the foregoing listed patents isherein incorporated by reference in its entirety.)

As previously noted, the ipsilateral transverse process of the inferiorvertebral bone of the target FSU may be removed to permit greater accessto the ipsilateral facet joint. If removed, the harvested bone can beused as autograft within the fusion bone mass used to fuse the superiorand inferior vertebral bones of the target FSU. The harvested bone maybe also placed into the intervertebral disc space to produce aninterbody fusion.) If the transverse process is not completely removed,then the ipsilateral facet joint may be reached using the trajectory ofmember 200. That trajectory extends across coronal plane T in a lateralto medial and anterior to posterior direction. The trajectory may besuperior to the ipsilateral transverse process, as shown in FIG. 10B.

A bone fastener can be passed sequentially via a lateral to medialtrajectory through the superior articulating process (SAP) of theinferior vertebral bone, across the joint space and then into theinferior articulating process (IAP) of the immediately superiorvertebral bone. The fastener may be further passed from a lateral tomedial trajectory into the ipsilateral lamina of the superior vertebralbone—as well be illustrated further below. The fastener is at leastpartially inserted through corridor C and follows an anterior toposterior trajectory across coronal plane T.

Specifically, a fastener may be placed into the ipsilateral facet jointin order to immobilize the movement between the superior and inferiorvertebral bones across said joint. Following a lateral to medialtrajectory (such as, e.g., the trajectory of member 200), the fastenermay be passed through the lateral aspect of the SAP of the inferiorvertebral bone, across the facet joint space and into the IAP of thesuperior vertebral bone, as indicated by arrow K in FIGS. 11A and 11B.Note that the fastener may be further passed into the ipsilateral lamina212 of the superior vertebra as shown in FIG. 11B. FIG. 11B illustratesa sectional view passing through the facet joints between the L3 and L4vertebral bones. The plane of the sectional view is shown by theanterior-posterior direction of arrow K in FIG. 11A. The lateral-medialdirection of arrow is shown in FIG. 11B.

Fasteners of any applicable design may be used. For example, FIGS. 12Aand 12 B illustrate a faster 240 comprising a bone screw 244 and awasher-like member 246. In one example, the head of screw may moveinside member 246 in at least one plane (such as, e.g., in aball-in-socket like design) so that shank 2442 may be positioned in oneof a plurality of different positions/angles relative to the centralaxis of the bore 2462 of member 246. While not illustrated, fastener 240may further comprises a locking feature that permits movement betweenscrew 244 and member 246 in a first configuration, and immobilizes screw244 relative to member 246 in a second configuration.

Many such locking features are known in the art and include amongothers, for example, a set screw that threadably engages member 246. Theset screw may be tightened into a second configuration to immobilizescrew 244 relative to member 246, or may be left untightened in a firstconfiguration, to permit movement between screw 244 and member 246. Inuse, screw 244 is passed into the ipsilateral facet joint (for example,using the trajectory of arrow K) until member 246 is forcibly positionedagainst the lateral, outer surface of the SAP of the inferior vertebra.The locking feature may be then transitioned from the firstconfiguration to the second configuration in order to immobilize screw244 relative to member 246.

FIGS. 13A and 13B illustrate implant 206 within the intervertebral discspace of the target FSU and fastener 240 immobilizing the ipsilateralfacet. Note that the ipsilateral transverse process is intact in FIG.13A and removed in FIG. 13B. While the distal aspect of screw 244 isillustrated passing into the ipsilateral lamina of the superiorvertebral bone, it may alternatively be placed in a trajectory thattraverses the TAP of the superior vertebra bone without extendingfurther into the ipsilateral lamina of the superior bone. Thistrajectory is shown in FIG. 14. Further, screw 244 may be angled evenmore inferiorly so that its distal aspect enters the lamina and/orspinous process of the inferior vertebral bone after traversing thefacet joint. The entry point may be, for example, at or near point “X”of FIG. 14.

FIG. 15 shows perspective views of bone fastener assembly 105, whileFIG. 16 shows a cross-sectional view of fastener assembly 105. Exemplarybone fastener assembly 105 includes a threaded bone screw 107 withthreaded shaft 1072 and a spherical head 1074. An internal bore 1076extends through the internal aspect of the screw 107, extending from thetop of head 1074 to the tip of shaft 1072. The internal bore has athreaded portion 1078. A hex-shaped receptacle 1079 resides within head1074. Receptacle 1079 is adapted to accept a screw driver (such as witha hex-shaped tip, or the like), wherein the driver can deliver arotational force to screw 107 and drive the threaded shaft into bone.

An outer housing 110 has an internal seat 1102 that is adapted to seathead 1074 of screw 107. Housing 110 has an additional seat 1104 that isadapted to accept an inter-connecting member, such as a rod. Threads1106 are adapted to compliment and accept threaded locking nut 116. Apusher member 114 is disposed between the two seat portions 1104 and1102 of housing 110 and transmits the downward force of the locking nut116 onto head 1074 (when an interconnecting rod is positioned betweenthe locking nut and pusher member 114).

An interconnecting member, such as a rod, may be positioned within seat1104 of housing 110. Specifically, the housing 110 and screw 107 aremoved into the desired relative spatial orientation. Locking nut 116 ispositioned above the seated interconnecting member and then threadablyadvanced relative to threads 1106 of housing 110. As locking nut 116 isadvanced, the interconnecting rod member is forced onto pusher member114. The pusher 114 is then forced downward onto head 1074 of screw1074, trapping the head between the pusher 116 and seat 1102. In thisway, full advancement of locking nut 116 produces rigid immobilizationof the interconnecting member, the housing 110 and the screw 107relative to one another.

It will be appreciated that screw assembly 105 is intended to beillustrative and non-limiting. Further, it will be understood that otherbone screw assemblies may be alternatively used and that multiple suchscrew assemblies are known in the art. For example, U.S. Pat. Nos.RE37665, 6,248,105; 6,371,957; 6,565,565; 6,641,586; and 7,704,271 eachdisclose at least one bone screw assembly that may be used to accomplishthe present method. Each of the foregoing U.S. patents is hereinincorporated by reference in its entirety. Any of these or any otherapplicable bone screw assemblies that are adapted to for use ininterconnecting neighboring bones may be alternatively or additionallyused.

FIG. 17 illustrates a method through which one or more bone fastenerassemblies 105 may be used to fixate a target spinal segment comprisingone or more FSUs. The fastener(s) may be passed through corridor C ontothe lateral aspect of the SAP of the inferior vertebral bone within eachFSU. Threaded shaft 1072 may be passed through the ipsilateral facetjoint and into the ipsilateral lamina of the superior vertebral bonevia, for example, trajectory K of FIG. 11. Alternatively, one or more offasteners assemblies 105 may be inserted into the vertebral boneswherein at least one fastener is anchored onto at least a portion of thepars interarticulais (either its true lateral surface, indicated as “B”in FIG. 17, or via a more posterior entry point and/or into theipsilateral lamina) without traversing the ipsilateral facet joint.Alternatively, in another embodiment, one or more fastener assemblies105 may be passed posterior to the pars interarticulatis and into thespinous process of the vertebral bone. Regardless of which of theaforementioned trajectories is employed, once inserted into vertebralbone, the fastener assemblies 105, disposed at different levels, may beinterconnected to each other via an interconnecting rod. While boneassemblies 105 are illustrated, it will be understood that other bonescrews and/or fastener assemblies may be additionally or alternativelyused to fixate into the vertebral bones via the disclosed method andtrajectory, and then interconnected with other fasteners/bone screwsdisposed at other levels. The interconnection may be performed byinterconnecting rods and/or interconnecting plates.

Note that the term “bone screw” is used as a generic term and mayinclude, but is not limited to, fastener assembly 105 or any otherappropriate bone screw/assembly that may be adapted to couple with aninterconnecting rod and/or plate. For example, the bone screw 107 ofbone fastener assembly 105 may serve, by itself, as a bone fastener foruse in any of the disclosed methods, since, at a minimum, it may becoupled with an interconnecting bone plate. Thus, the terms “bone screw”and “bone fastener assembly” user herein may be used interchangeably andimply that screw/fastener assembly may be coupled to an interconnectingmember, such as a plate or a rod. Bone screws may be also used asfreestanding, uncoupled fasteners that are driven across more than onebone in order to fixate these bones to one another.

FIGS. 18A and 18B illustrate an additional exemplary method throughwhich bone screw(s)/fastener assemblies may be used to fixate a targetspinal segment comprising one or more FSUs. The bone screw(s)/fastenerassemblies may be passed through corridor C onto the lateral aspect ofthe ipsilateral pedicle and traverse, at least partially, a portion ofthe pedicle. In one example, the bone screw fastener assembly extendsthrough the pedicle in both a lateral to medial and anterior toposterior trajectory, as shown in FIG. 18A. The distal segment of thebone screw/fastener assembly may be further advanced into the laminaand/or spinous of the vertebral bone containing the pedicle into whichthe screw is inserted (FIG. 18A). While the bone screw/fastener assemblyappears to be positioned on top (i.e., the superior aspect) of the leftpedicle, it is understood that this depiction is for illustrativepurposes only and the actual path extends through the substance of thepedicle and vertebral bone. In FIG. 18A, the bone screw/fastenerassembly appears similar to screw 107 of assembly 105 (FIGS. 16 and 17)for illustrative simplicity. However, as stated above, any bonescrew/fastener assembly may be additionally or alternatively used.

In an exemplary embodiment, as shown in FIG. 18A, the bone screw entrypoint is preferably posterior to coronal plane V and anterior to coronalplane T. Coronal plane U was previously defined and coronal plane V maybe defined as parallel to and 15 mm anterior to coronal plane U. Asstated elsewhere herein, it will be understood that the vertebral bodiesmay vary in actual anatomy from the idealized vertebral bonesillustrated herein, whether from congenital or acquired deformity,spondylotic change (such as bony spurs and the like), spinalmalalignment or other changes, and for descriptive purposes an idealizedvertebral bones are assumed.

FIG. 18B illustrates a lateral view of an FSU with the bone screw ofFIG. 18A inserted into the lateral aspect of the L4 pedicle. As notedabove, the bone screw may take an anterior to posterior and lateral tomedial trajectory within the substance of the bone. An exemplary axialtrajectory of the bone screw, trajectory T5, is shown in FIG. 18B. Notethat lateral surface of the pedicle provides an access window betweenthe nerve root above (L3 nerve root) and the nerve below (L4 nerveroot). As segment of the lateral aspect of the pedicle is devoid ofnerves, as well be discussed further below, this segment may be used asthe entry point for the bone screw.

FIG. 19A illustrates a view of a lateral aspect of an FSU, while FIG.19B shows a coronal section taken along plane M. Note that the pediclesof adjacent vertebrae are vertically aligned while the nerves exit at anangle between the adjacent pedicles. For example, the left L3 pedicle isvertically positioned above the left L4 pedicle and the left L3 nerveroot exits the spinal canal in an oblique trajectory that extends fromsuperior/medial to inferior/lateral. This provides two segments,segments K1 and K2, through which one may traverse a horizontal plane ofthe FSU without encountering the nerves. Segment K1 is known to those ofordinary skill in the art as “Kambin's triangle”. (See CadavericAnalysis of the Kambin's Triangle. By Hoshide R, Feldman E, et al.Cureus. 2016 Feb. 2; 8 (2), which is herein incorporated by reference inits entirety.)

Segment K2 is previously undescribed and may be an additional oralternate location for bone screw insertion into a vertebral bone. Forexample, the lateral aspect of the pedicle of the vertebral bone to beinstrumented can be approached through corridor C. A bone screw may beinserted into the lateral aspect of the pedicle and/or proximalvertebral body through segment K2, using a bone entry point that isanterior to coronal plane T and/or posterior to coronal plane V (FIG.18A). The subsequent trajectory of the bone screw within the vertebralbone may be, for example, the trajectory shown in FIGS. 18A and 18B.

A known pathway for bone screw insertion within the posterior aspect ofthe vertebral bone is the “cortical bone screw trajectory” and isdescribed in, among other citations, Cortical bone trajectory for lumbarpedicle screws, Santoni B G, Hynes R A, et al. Spine J. 2009 May; 9(5):366-73, which is herein incorporated by reference in its entirety.In the cortical bone screw trajectory, the bone screw is inserted intothe posterior surface of the vertebral bone, often immediately medial tothe vertebral bone's superior facet joint (i.e., the facet joint formedby that vertebral bone's SAP and the IAP of the immediately superiorvertebral bone). The bone screw is guided in a medial to lateraltrajectory as it is advanced anteriorly into the vertebral bone (forexample, as depicted in FIG. 23B).

In one implementation of the current invention, a bone screw is insertedinto a lateral surface of vertebral bone such as, e.g., into segment K2.The bone entry point for screw insertion may be between coronal plane Tand coronal plane V in the anterior to posterior direction and betweenthe superior bony surface of the vertebral body being instrumented andthe horizontal plane of the most inferior point of the ipsilateralpedicle. The screw trajectory in the vertebral bone is substantially 180degree to that of the known cortical bone screw trajectory that isdescribed above. In other words, the bone screw of this method is guidedin a lateral to medial trajectory as it is advanced posteriorly into thevertebral bone from the bone insertion point, having a trajectorysimilar to that depicted in FIG. 18A.

In an additional implementation, one or more bone screws may be attachedanteriorly, directly onto the body of the vertebral bone. For example,the vertebral body may be accessed using the direct anterior approach505, the antero-lateral approach 507 and/or the direct lateral approach509 of FIG. 5. Any other known approach to access the antero-lateralsurfaces of the vertebral body through a skin incision made anterior tocoronal plane T may be additionally or alternatively used. At least onebone screw is advanced into the vertebral body and then directedposteriorly in order to have the distal aspect of the screw exit thevertebral body at least partially through the vertebral body-pediclejunction and enter the anterior aspect of the contralateral pedicle.(The body-pedicle junction is a vertical segment of bone wherein theanterior end of the pedicle joins the posterior vertical surface of thevertebral body.)

The foregoing method of bone screw placement is illustrated in FIG. 20A,wherein the screw trajectory is selected so that the distal aspect ofthe bone screw may, at least partially, traverse the contralateralpedicle, in a medial to lateral direction, and may, but not necessarily,exit the lateral wall of the pedicle at, for example, segment K2 (FIG.19B). Specifically, FIG. 20A illustrates the screw trajectory using bonescrew 207. One or more additional bone screws 210 may be also employed.The screws are illustrated as being joined by a plate 250, wherein plate250 is then anchored to another vertebral bone by additional bonesscrews (not shown).

Alternatively, bone screw assemblies, such as, e.g., bone screw assembly105 of FIGS. 15 and 16, may be placed into the vertebral bone using thesame method/trajectory and then connected to additional bone screws atadjacent vertebral levels by an interconnecting rod (instead of aplate). It will be understood that various bone plate are known in theart and that any applicable bone plate may be additionally oralternatively used. Further, many bone plates include features andspecialized sub-segments, such as, e.g., screw to plate lockingfeatures, slots that allow bone screws to move/subside therein, movablesub-segments, expandable size configurations, and the like. On or moreof these features may be included, where appropriate, in generic plate250.

An additional implementation for the method of bone screw placement isshown in FIG. 20B. While similar to that of FIG. 20A, the screwtrajectory in this implementation is selected so that the distal aspectof the bone screw passes through the body-pedicle junction and entersthe anterior aspect of the ipsilateral pedicle. As in FIG. 20A, one ormore additional bone screws 210 may be also employed at each vertebrallevel and bone screws at different vertebral bones may be coupled by useof an interconnecting plate and/or rod.

While various embodiments with different bone screw trajectories havebeen illustrated, it will be understood that screws having differingtrajectories can be combined to form additional embodiments. Forexample, a target FSU may be approached using a single corridor to thevertebral bodies of the FSU's superior and inferior vertebral bones. Theincision is preferably positioned anterior to coronal plane T (shown inFIGS. 3 and 5) and the corridor formed between the incision and thespine is developed through the extra-spinal and non-bony tissues of theabdominal cavity. The corridor may be at least partially containedwithin the retro-peritoneal space.

Once the spine is reached, the intervertebral disc space of the targetFSU is accessed and an orthopedic implant may be positioned inside ofthe disc space after removal of at least a portion of the natural discmaterial that is contained therein. The intervertebral disc space can beaccessed through the direct anterior approach 505, the antero-lateralapproach 507, and/or the direct lateral approach 509 of FIG. 5. Animplant that is placed within the disc space may be a device configuredto produce a bone fusion between the superior and inferior vertebralbones of the target FSU. Further, the implant can be positioned tooverly at least segment of apophyseal ring (FIG. 5) of the superiorand/or inferior vertebral bone of the target FSU, as illustrated byimplant 510 shown in FIG. 21A.

After implant placement, at least one bone screw may be advanced intothe each of the superior and inferior vertebral bodies of the targetFSU. At least one bone screw is positioned into each of the bodies ofthe two vertebral bones of the target FSU. The screw(s) in each of thesuperior and inferior bodies of the target FSU can be theninterconnected with a plate and/or a rod. Using the same corridorthrough the extra-spinal tissues of the abdominal cavity, at least oneadditional bone screw may be placed into the portion of the FSU that isposterior to coronal line T. This additional screw may be advanced in ananterior to posterior direction across coronal plane T and then guidedacross the ipsilateral facet joint of the FSU (FIG. 11). Thistrans-facet screw then traverses the SAP of the inferior vertebral bone(from lateral to medial) and the space of the facet joint, and entersthe TAP of the superior vertebral bone of the target FSU (FIG. 14).

Alternatively, a first bone screw may be advanced in an anterior toposterior direction across coronal plane T and then guided into theinferior vertebral bone of the target FSU (with or without traversing asegment of the superior vertebral bone). A second bone screw may be alsoadvanced from an anterior to posterior direction across coronal plane Tand then guided into the superior vertebral bone of the target FSU (withor without traversing a segment of the inferior vertebral bone). Thefirst and second bone screws may subsequently be interconnected using arod and/or plate. (As noted above, the term “bone screw” as used hereinmay include, without limitation, bone screw assembly 105 of FIG. 15 orany other appropriate bone screw that is adapted to couple with aninterconnecting rod and/or plate.) In this embodiment, the first and/orsecond bone screw may be advanced into bone using the trajectoryillustrated in FIGS. 18A and 18B (and discussed above).

FIG. 21B illustrates an example implementation wherein at least one bonescrew is positioned into the vertebral body anterior to coronal plane Tand at least one additional screw is advanced from an anterior toposterior direction across coronal plane T and is, at least partially,anchored to a segment of the vertebral bone that is posterior to coronalplane T. Note that additional bone screws (for example, anothervertebral body screw) may be also employed, such as bone screw 210. Forexample, at least one bone screw of one of the vertebral bodies may bepositioned so that its distal aspect enters the contralateral pedicle,as shown in FIG. 20A. A plate (or rod), such as, e.g., plate 250, may beused to couple some of the bone screws that are anchored within onevertebral bone to bone screws anchored into other vertebral bones.

An exemplary method for access and possible instrumentation of ananterior and posterior aspect of the target FSU through a singleabdominal corridor having a starting point at a skin that is anterior tocoronal plane T is described above. Additional access of the posterioraspect of the FSU may be achieved by making a skin incision posterior tocoronal plane T (for example, on the skin of the back of a subject)approaching the spine from a posterior to anterior trajectory. Thelatter exemplary method is illustrated in FIG. 22 wherein the anterioraspect of the FSU may be accessed through at least one of the approachesof FIG. 5 (i.e., approaches 505, 507 and 509) and the posterior aspectof the FSU may be accessed through corridor C, as previously described,as well as through corridor P shown in FIG. 22. Access of the FSUthrough corridor P allows for direct bone screw placement along thelongitudinal access of the pedicle (FIG. 23A) and/or along the corticalbone screw trajectory discussed above (FIG. 23B). While the illustratedbone screw is placed in the right side of the vertebral bone, it isunderstood that the bone screw placement trajectories of FIGS. 23A and23B may be employed on either side of the vertebral bone.

The addition of corridor P in accessing the target FSU allows bothcorridors to intersect at the level of the transverse process (as shownin FIG. 24), thereby providing a direct and continuousanterior/posterior corridor to the FSU. This method allowscircumferential access to the vertebral bone, as shown by the areawithin the uneven broken lines of FIG. 24, while the patient is in asingle position (such as, e.g., the lateral decubitus position) withoutthe need to reposition the patient on the operating room table and torepeat the surgical preparation and drape process. It also allows forconcurrent to anterior and posterior work, wherein a first surgeon worksthrough corridor C while a second surgeon works through corridor P. Aspreviously noted, the transverse process may be removed, if desired, andthis removal will further increase the size of the directanterior/posterior corridor, as shown in FIGS. 25A-25C. This wideraccess can be used to provide comprehensive decompression of the neuraltissues within the spinal canal. It can also be used to correct spinaldeformity with greater ease and safety than is currently available usingconventional methods.

FIG. 26 illustrates an example of deformity correction that may beachieved with the anterior/posterior access to the FSU methodologydiscussed above. The access corridor allows for more complete release(which comprises releasing the connections between adjacent vertebralbone) so that vertebral realignment can be performed. Limited release ofadjacent vertebral bone is a major factor in suboptimal surgicalrealignment of the vertebral bones. The enlarged access window will alsoallow more thorough resection of vertebral segments in order to optimizethe desired curvature in the post-operative spine.

FIG. 26 illustrates an example of segmental resection of the shaded areain order to produce a greater lordotic angle across the segment. Thelordotic angle may be measured as the angle between the superior surfaceof a superior vertebral bone and the inferior surface of an inferiorvertebral bone. The shaded area is removed from the left lateral sidewall of the vertebral bone to the right lateral side wall of thevertebral bone. This procedure is known to those of ordinary skill inthe art as a “pedicle subtraction osteotomy” and is described in detailin Decision Making Regarding Smith-Petersen vs. Pedicle SubtractionOsteotomy vs. Vertebral Column Resection for Spinal Deformity byBridwell, K H. SPINE Volume 31, Number 19 Suppl, pp S171-S178 2006,which is herein incorporated by reference in its entirety.

The procedure may be performed with less morbidity when at least aportion of the osteotomy (such as, e.g., the segment involving removalof the pedicle and/or body segment) is performed through corridor C.Note that the lordotic angle, while increased in FIG. 26B by closing thebony defect after the osteotomy, may be increased further by positioninga lordosis implant between the bony surfaces to be re-apposed (FIG.26C). In fact, the implant may be adjustable in its lordotic (or evenkyphotic) angle so that the surgeon may further adjust the angle acrossthe target FSU after the implant has been positioned within theosteotomy site.

The totality of the above described methods, from selection of thetarget level to implant to the final placement of implant, can beperformed under imaging guidance (such as X-ray, CT, MRI,computer-guided imaging and the like). Further, the operation can beperformed using percutaneous or minimally invasive surgical techniqueswith or without the aid of electrophysiological monitoring. The latterinclude techniques such as electromyography (EMG), somato-sensory, motorevoked potentials and the like. These and other techniques may be usedand are intended to alert the operating surgeon to the presence ofnerves and other neural elements within the surgical corridor. Forexample, EMG identification of nerves permits the surgeon to navigatethe surgical site with increased safety and lessens the possibility ofnerve injury.

The devices disclosed herein and/or any of their components can be madeof any biologically adaptable or compatible materials. Materialsconsidered acceptable for biological implantation are well known andinclude, but are not limited to, stainless steel, titanium, tantalum,combination metallic alloys, various plastics (such as PEEK and thelike), resins, ceramics, biologically absorbable materials and the like.Any components may be also coated/made with osteo-conductive (such asdeminerized bone matrix, hydroxyapatite, and the like) and/orosteo-inductive (such as Transforming Growth Factor “TGF-B,”Platelet-Derived Growth Factor “PDGF,” Bone-Morphogenic Protein “BMP,”and the like) bio-active materials that promote bone formation. Further,any surface may be made with a porous ingrowth surface (such as, e.g.,porous titanium, titanium wire mesh, plasma-sprayed titanium, tantalum,porous CoCr, and the like) and/or provided with a bioactive coating,(such as tantalum, and/or helical rosette carbon nanotubes or othercarbon nanotube-based coating) in order to promote bone in-growth orestablish a mineralized connection between the bone and the implant, andto reduce the likelihood of implant loosening. The system or any of itscomponents may be made by “additive manufacturing”, such as, e.g., “3D”printing. Lastly, the system or any of its components can also beentirely or partially made of a shape memory material or otherdeformable material.

While this specification contains many specific examples andembodiments, these should not be construed as limitations on the scopeof what is claimed or of what may be claimed, but rather as descriptionsof features specific to particular embodiments. Certain features thatare described in this specification in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable sub-combination.

Moreover, although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asub-combination or a variation of a sub-combination. Similarly, whileoperations are depicted in the drawings and/or described in thespecification in a particular order, this should not be understood asrequiring that such operations be performed in the particular ordershown or in sequential order, or that all illustrated operations beperformed, to achieve desirable results. Only a few examples andimplementations are disclosed. Variations, modifications andenhancements to the described examples and implementations and otherimplementations may be made based the present disclosure.

What is claimed is:
 1. A method for stabilizing a functional spinal unitof a subject, the functional spinal unit comprising a superior vertebralbone, an immediately inferior vertebral bone, and an intervertebral discspace disposed there between, the method comprising: forming a skinincision in the subject, the skin incision positioned anterior to afirst coronal plane, wherein the first coronal plane: (i) defines avertical plane of the subject, (ii) comprises at least a portion of aposterior wall of the superior vertebral bone and (iii) divides thefunctional spinal unit into an anterior segment and a posterior segment;forming a surgical corridor, the surgical corridor extending from theskin incision and traversing at least a portion of an abdominal cavityof the subject; extending a first branch of the surgical corridor to theposterior segment of the functional spinal unit, the first branchextending posterior to the first coronal plane and posterior to at leasta segment of a psoas muscle, the psoas muscle positioned ipsilateral tothe skin incision; forming an entry point in an outer bony surface of alateral wall of a first pedicle of at least one of the superiorvertebral bone or the inferior vertebral bone, the entry point locatedbetween a first nerve positioned immediately below the first pedicle anda second nerve positioned above the first pedicle, wherein the lateralwall is positioned posterior to the first coronal plane and ipsilateralto the skin incision; and advancing a first fastener through the entrypoint and into a posterior segment of the vertebral bone comprising thefirst pedicle, the first fastener traversing a trajectory having bothanterior to posterior and lateral to medial components.
 2. The method ofclaim 1, wherein at least a portion of the surgical corridor traversesan anterior layer of a thoracolumbar fascia positioned ipsilateral tothe skin incision.
 3. The method of claim 2, wherein the advancing thefirst fastener comprises advancing the first fastener through a laminasegment of the superior vertebral bone.
 4. The method of claim 2,wherein the advancing the first fastener comprises advancing the firstfastener through a lamina segment of the inferior vertebral bone.
 5. Themethod of claim 2, further comprising manipulating a first facet jointof the functional spinal unit, the first facet joint positionedipsilateral to the skin incision.
 6. The method of claim 5, furthercomprising removing at least a segment of the first facet joint.
 7. Themethod of claim 5, further comprising immobilizing the first facet jointof the functional spinal unit.
 8. The method of claim 7, furthercomprising advancing the first fastener in a lateral to medialtrajectory at least though a portion of the first facet joint.
 9. Themethod of claim 2, further comprising removing at least a bony segmentof a transverse process of the functional spinal unit, the transverseprocess positioned ipsilateral to the skin incision.
 10. The method ofclaim 2, further comprising advancing an implant at least partially intothe intervertebral disc space.
 11. The method of claim 10, furthercomprising implanting a substance configured to form bone into theintervertebral disc space.
 12. The method of claim 11, wherein at leasta portion of the substance configured to form bone is comprised of abony segment of a transverse process of the functional spinal unit. 13.The method of claim 1, further comprising advancing a second fastenerinto an other one of the superior vertebral bone or the inferiorvertebral bone.
 14. The method of claim 13, further comprisingpositioning an interconnecting member to couple with each of the firstfastener and the second fastener.
 15. The method of claim 1, furthercomprising advancing a second fastener in a medial to lateral directioninto a second pedicle of the functional spinal unit, the second pediclepositioned contralateral to the skin incision.
 16. A method fortreatment of a functional spinal unit of a subject, the functionalspinal unit comprising a superior vertebral bone, an inferior vertebralbone and an intervertebral disc space disposed there between, the methodcomprising: positioning the subject in a first position on an operatingtable; forming a first skin incision in the subject, the first skinincision positioned anterior to a first coronal plane, wherein the firstcoronal plane: (i) defines a plane of the subject that extends from ananterior-most point of a right transverse process of the inferiorvertebral bone to an anterior-most point of a left transverse process ofthe inferior vertebral bone; and (ii) divides the functional spinal unitinto an anterior segment and a posterior segment; forming a firstsurgical corridor extending from the first skin incision and traversingat least a portion of an abdominal cavity of the subject; advancing anorthopedic implant through at least a segment of the first surgicalcorridor and at least partially into the intervertebral disc space ofthe functional spinal unit; extending a first branch of the firstsurgical corridor onto the posterior segment of the functional spinalunit, the first branch extending posterior to the first coronal planeand traversing an anterior layer of a thoracolumbar fascia, wherein thethoracolumbar fascia is positioned ipsilateral to the first skinincision; forming a second skin incision in a posterior aspect of thesubject; forming a second surgical corridor extending from the secondskin incision to a lamina portion of at least one of the superiorvertebral bone or the inferior vertebral bone; and connecting the firstand second surgical corridors within the subject to form a combinedsurgical corridor.
 17. The method of claim 16, wherein the combinedsurgical corridor provides access to at least a side aspect and aposterior aspect of the functional spinal unit.
 18. The method of claim16, further comprising manipulating a first facet joint of thefunctional spinal unit, the first facet joint positioned ipsilateral tothe first skin incision.
 19. The method of claim 18, further comprisingremoving at least a segment of the first facet joint.
 20. The method ofclaim 18, further comprising immobilizing the first facet joint of thefunctional spinal unit.
 21. The method of claim 16, further comprisingadvancing a first fastener through a first pedicle of the inferiorvertebral bone, the first pedicle positioned ipsilateral to the skinincision, wherein the first fastener traverses the first pedicle in ananterio-lateral to posterio-medial direction.
 22. The method of claim21, further comprising advancing a second fastener through a secondpedicle of the superior vertebral bone, the second pedicle positionedipsilateral to the skin incision, wherein the second fastener traversesthe second pedicle in an anterio-lateral to posterio-medial direction.23. The method of claim 22, further comprising positioning aninterconnecting member to couple with each of the first fastener and thesecond fastener, wherein the positioning limits movement between thesuperior vertebral bone and the inferior vertebral bone.
 24. The methodof claim 22, further comprising advancing a third fastener in a medialto lateral direction into a third pedicle of the functional spinal unit,the third pedicle positioned contralateral to the skin incision.
 25. Themethod of claim 16, further comprising implanting a bone formingmaterial into the intervertebral disc space, wherein at least a portionof the bone forming material comprises a bony segment of a transverseprocess of the functional spinal unit.
 26. The method of claim 16,further comprising removing at least a lamina segment of the functionalspinal unit.
 27. The method of claim 16, further comprising removing atleast a segment of a vertebral body of the functional spinal unit. 28.The method of claim 27, further comprising removing a pedicle portion ofthe functional spinal unit.
 29. A method for treatment of a functionalspinal unit of a subject, the functional spinal unit comprising asuperior vertebral bone, an inferior vertebral bone, and anintervertebral disc space disposed there between, the method comprising:forming a skin incision in the subject, the skin incision positionedanterior to a first coronal plane of the subject, wherein the firstcoronal plane: (i) comprises at least a portion of a posterior wall ofthe superior vertebral bone, and (ii) divides the functional spinal unitinto an anterior segment and a posterior segment; forming a surgicalcorridor, the surgical corridor extending from the skin incision andtraversing at least a portion of an abdominal cavity of the subject;forming a first branch off of the surgical corridor, the first branchextending: (i) to the posterior segment of the functional spinal unit;(ii) posterior to the first coronal plane; and (iii) posterior to atleast a segment of a psoas muscle, the psoas muscle being ipsilateral tothe skin incision; forming an entrance in an outer bony surface of alateral wall of a first pedicle, the first pedicle part of either thesuperior vertebral bone or the inferior vertebral bone, the entranceformed between a first nerve positioned below the first pedicle and asecond nerve positioned above the first pedicle, wherein the lateralwall is posterior to the first coronal plane and ipsilateral to the skinincision; and advancing a first fastener through the entrance and into aposterior segment of the either the superior vertebral bone or theinferior vertebral bone, the first fastener traversing a trajectorywhich is at least both (i) anterior-to-posterior, and (ii)lateral-to-medial.